Method for fabricating package structure

ABSTRACT

A package structure and a method for fabricating the same are provided. An electronic component such as a sensing chip and a conductive element such as a bonding wire are mounted to a carrier, encapsulated by an encapsulant, and electrically connected through a conductive layer. As such, the electronic component can further be electrically connected to the carrier through the conductive layer and the conductive element. Therefore, the sensing chip can be packaged through current packaging processes, thereby reducing the fabrication cost, shortening the fabrication time and improving the product yield.

BACKGROUND 1. Technical Field

The present disclosure relates to semiconductor package structures, and,more particularly, to a sensor-type package structure.

2. Description of Related Art

Nowadays, as people are paying more and more attention on privacyprotection, many high-end electronic products are equipped with useridentification systems to improve data security. Therefore, research anddevelopment of identification systems are becoming increasinglyimportant in electronic industries.

Generally, biological identification systems can identify physiologicalfeatures such as fingerprints, pupils, faces and voiceprints, oridentify behavioral features such as signatures or voices. Physiologicalfeature identification systems have advantages of uniqueness, highsecurity and convenience and therefore are widely accepted by consumers.

Further, as high-end electronic products are developed toward the trendof high integration, they are usually equipped with physiologicalfeature identification devices such as fingerprint identificationdevices or face identification devices. Currently, fingerprintidentification devices are the most widely used devices since suchdevices facilitate to meet the miniaturization requirement of electronicproducts. Fingerprint identification devices are divided into opticalfingerprint identification devices that can optically scan fingerprintpatterns and silicon fingerprint identification devices that can detectfaint electrical charges in fingerprint patterns.

FIG. 1 is a schematic cross-sectional view of a conventional fingerprintsensing package structure 1. A plurality of through silicon vias (TSVs)12 are formed corresponding in position to a plurality of electrode pads100 that are disposed at an edge of a chip body 10. The TSVs 12 areformed by a dry etching process. A conductive layer 14 is formed in theTSVs 12 and extends to a lower side of the chip body 10. An insulatinglayer 13 is further formed on the conductive layer 14 to prevent aleakage from occurring between the TSVs 12. A portion of the conductivelayer 14 is exposed from the insulating layer 13 to serve as electricalcontacts. A solder material 15 is bonded to the electrical contacts.

However, since the TSVs 12 are positioned at the edge of the chip body10 and the edge of the chip body 10 has a small thickness, cracking mayoccur to the TSVs 12.

Further, the dry etching process for forming the TSVs 12 and the processfor forming the insulating layer 13 in the TSVs 12 complicate thefabrication process, increase the fabrication time and adversely affectthe product yield.

Therefore, there is a need to provide a package structure and afabrication method thereof so as to overcome the above-describeddrawbacks.

SUMMARY

In view of the above-described drawbacks, the present disclosureprovides a package structure and a method for fabricating the same so asto reduce the fabrication cost, shorten the fabrication time and improvethe product yield.

The package structure according to the present disclosure comprises: acarrier; an electronic component disposed on the carrier and having asensing surface; at least one conductive element disposed on thecarrier; an encapsulant formed on the carrier to encapsulate theelectronic component and the conductive element, wherein the sensingsurface of the electronic component and a portion of a surface of theconductive element are exposed from the encapsulant; and a conductivelayer formed on the encapsulant and electrically connecting theconductive element and the electronic component.

The method for fabricating a package structure according to the presentdisclosure comprises the steps of: disposing at least one conductiveelement and an electronic component having a sensing surface on acarrier; forming on the carrier an encapsulant that encapsulates theelectronic component and the conductive element, wherein the sensingsurface of the electronic component and a portion of a surface of theconductive element are exposed from the encapsulant; and forming on theencapsulant a conductive layer that electrically connects the conductiveelement and the electronic component.

In an embodiment, the carrier is a circuit board or a lead frame.

In an embodiment, the electronic component is a fingerprintidentification chip.

In an embodiment, the conductive element is a loop-type bonding wire ora wire segment.

In an embodiment, the conductive element is electrically connected tothe carrier.

In an embodiment, an opening is formed in the encapsulant to expose theportion of the surface of the conductive element.

In an embodiment, the electronic component, the conductive element andthe encapsulant are disposed on one side of the carrier, and a pluralityof conductive pads are formed on the other opposite side of the carrier.

Therefore, since the conventional TSV is replaced with the conductiveelement, the present disclosure fabricates the package structure throughcurrent packaging processes, dispensing with the conventionalTSV-related processes. As such, the present disclosure reduces thefabrication cost, shortens the fabrication time and improves the productyield.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view of a conventional fingerprintsensing package structure;

FIGS. 2A to 2E are schematic cross-sectional views showing a method forfabricating a package structure according to the present disclosure,wherein FIG. 2C′ is a schematic perspective view of FIG. 2C, and FIG.2E′ is a schematic plan view of FIG. 2E; and

FIGS. 3A to 3C are schematic cross-sectional views showing otherembodiments of FIG. 2E, wherein FIG. 3A′ shows another embodiment ofFIG. 3A.

DETAILED DESCRIPTION OF EMBODIMENTS

The following illustrative embodiments are provided to illustrate thedisclosure of the present disclosure, these and other advantages andeffects can be apparent to those in the art after reading thisspecification.

It should be noted that all the drawings are not intended to limit thepresent disclosure. Various modifications and variations can be madewithout departing from the spirit of the present disclosure. Further,terms such as “on”, “a” etc. are merely for illustrative purposes andshould not be construed to limit the scope of the present disclosure.

FIGS. 2A to 2E are schematic cross-sectional views showing a method forfabricating a package structure 2 according to the present disclosure.

Referring to FIG. 2A, an electronic component 21 is disposed on acarrier 20 and a plurality of conductive elements 22 are disposed on thecarrier 20. Then, an encapsulant 23 is formed on the carrier 20 toencapsulate the electronic component 21 and the conductive elements 22.

In an embodiment, the carrier 20 is a circuit board, such as packagingsubstrate having circuits or a semiconductor board. The electroniccomponent 21 is a sensing chip that is used to detect changes inelectrical charges, temperature or pressure of a living organism.Preferably, the electronic component 21 is a fingerprint identificationchip that performs a biological identification based on a capacitancedifference received from a sensing area. The electronic component 21 hasa sensing surface 21 a with a plurality of electrode pads 210, and anon-sensing surface 21 b opposite to the sensing surface 21 a and bondedto the carrier 20 through an adhesive layer 200 such as an epoxy resinfilm.

The carrier 20 has a plurality of conductive pads 201 on an upper sidethereof and a plurality of conductive pads 202 on a lower side thereof.The conductive pads 202 are used for connecting the carrier 20 to anelectronic device (not shown), such as a circuit board, a package or thelike. The conductive elements 22 are in contact with and bonded to theconductive pads 201 so as to be electrically connected to the carrier20. Each of the conductive elements 22 is a bonding wire segment, oneend 22 a of which is bonded to the corresponding conductive pad 201 ofthe carrier 20. In an embodiment, at least one of the conductive pads201 is electrically grounded for subsequently conducting electrostaticcharges through internal circuits of the carrier 20 (not shown) and theconductive pads 202 to a circuit board (not shown) disposed on the lowerside of the carrier 20.

In an embodiment, the encapsulant 23 is formed by molding on the carrier20 to encapsulate the electronic component 21 and the conductiveelements 22. The encapsulant 23 has a first surface 23 a bonded to thecarrier 20 and a second surface 23 b opposite to the first surface 23 a.The sensing surface 21 a of the electronic component 21 is exposed fromthe second surface 23 b of the encapsulant 23. In an embodiment, thesensing surface 21 a of the electronic component 21 is flush with thesecond surface 23 b of the encapsulant 23. In another embodiment, duringthe molding process, a film is attached to an upper mold to cover theelectrode pads 210, thus preventing the encapsulant 23 from being formedon and covering the electrode pads 210. After the molding process, theupper mold is removed to expose the electrode pads 210.

Referring to FIG. 2B, a plurality of openings 230 are formed on thesecond surface 23 b of the encapsulant 23 to expose the other ends 22 bof the conductive elements 22.

In an embodiment, the encapsulant 23 is already cured and therefore theopenings 230 are formed by laser. Further, since a small number (forexample, 18) of the fingerprint identification chip are provided, thelaser process for forming the openings 230 has advantages of lowfabrication cost and short fabrication time. If the cured encapsulant 23is etched by an etching solution, a specific mask pattern and relatedprocesses such as exposure and development are required and thefabrication is difficult and not cost-effective.

Referring to FIG. 2C, a resist layer 25 is formed on a portion of thesecond surface 23 b of the encapsulant 23 and a portion of the sensingsurface 21 a of the electronic component 21, and a plurality of openareas 250 are formed in the resist layer 25 to expose the openings 230,the electrode pads 210 and the area between the openings 230 and theelectrode pads 210.

In an embodiment, referring to FIG. 2C′, the open areas 250 are formedby laser ablation 9.

Referring to FIG. 2D, a conductive layer 24 is formed in the open areas250 for electrically connecting the conductive elements 22 and theelectrode pads 210 of the electronic component 21.

In an embodiment, the electronic component 21 is electrically connectedto the carrier 20 through the conductive layer 24 and the conductiveelements 22. In another embodiment, the conductive layer 24 is formed inthe openings 230 so as to be in contact with the ends 22 b of theconductive elements 22.

In an embodiment, the conductive layer 24 can be formed byelectroplating, sputtering or depositing a metal material. In anotherembodiment, the conductive layer 24 has a stainlesssteel/copper/stainless steel structure. In yet another embodiment, aconductive adhesive such as silver adhesive can be filled in the openareas 250, heated and cured to serve as the conductive layer 24.

In an embodiment, the conductive layer 24 can extend from one of theopenings 230 to the second surface 23 b of the encapsulant 23. As such,the encapsulant 23 is grounded to the carrier 20 through the conductivelayer 24 and the corresponding conductive element 22. Therefore, when auser presses the fingerprint sensor with his finger, the conductivelayer 24 can conduct electrostatic charges of the finger. In anembodiment, the opening 230 can be filled with the conductive layer 24.

Referring to FIGS. 2E and 2E′, the resist layer 25 is removed and apackage structure 2 is obtained.

FIG. 3A is a schematic cross-sectional view of a package structure 3according to another embodiment of the present disclosure. Referring toFIG. 3A, each of the conductive elements 32 is a loop-type bonding wire,and the conductive layer 24 is in contact with a loop top 32 c of theconductive element 32. Alternatively, referring to FIG. 3A′, when theopening 230 is formed by laser, the conductive element 32 is burned intotwo separate segments. Each of the segments has an end exposed from theopening 230 and in contact with the conductive layer 24. The conductiveelement 22, 32 can be a bump containing a solder material or copper, ametal post, or a metal frame.

FIGS. 3B and 3C are schematic cross-sectional views of packagestructures 3′, 3″ according to other embodiments of the presentdisclosure. Referring to FIGS. 3B and 3C, the carrier 30 can be a leadframe having a die attach pad 300 and a plurality of leads 301. Theelectronic component 21 is disposed on the die attach pad 300 and theconductive elements 22 and 32 are disposed on the leads 301. The leads301 can be exposed from the encapsulant 23 according to the practicalneed. In an embodiment, the exposed portions of the leads 301 can benotched (as shown in FIG. 3B) or flat (as shown in FIG. 3C).

The method according to the present disclosure can be performed throughcurrent packaging processes, thus dispensing with the conventionalTSV-related processes such as a dry etching process and processes forforming an insulating layer and a photoresist layer. That is, theconventional TSVs are replaced with the conductive elements 22 and 32.Therefore, the present disclosure reduces the fabrication cost, shortensthe fabrication time and improves the product yield.

Further, the conductive elements 22 and 32 and the conductive layer 24can be fabricated by current equipment, thus reducing the fabricationcost.

In an embodiment, a portion of the surfaces of the conductive elements22 and 32 can be flush with the second surface 23 b of the encapsulant23 so as to be exposed from the second surface 23 b of the encapsulant23.

The present disclosure further provides a package structure 2, 3, 3′,3″, which has: a carrier 20, 30; an electronic component 21 disposed onthe carrier 20 and having a sensing surface 21 a; at least oneconductive element 22, 32 disposed on and electrically connected to thecarrier 20; an encapsulant 23 formed on the carrier 20 to encapsulatethe electronic component 21 and the conductive element 22, 32, whereinthe sensing surface 21 a of the electronic component 21 and a portion ofa surface of the conductive element 22, 32 (an end 22 b or a loop top 32c) are exposed from the encapsulant 23; and a conductive layer 24 formedon the encapsulant 23 for electrically connecting the conductive element22, 32 and the electronic component 21.

In an embodiment, the carrier 20, 30 is a circuit board or a lead frame.

In an embodiment, the electronic component 21 is a fingerprintidentification chip.

In an embodiment, the conductive element 22, 32 is a loop-type bondingwire or wire segment.

In an embodiment, an opening 230 is formed in the encapsulant 23 toexpose the portion of the surface of the conductive element 22, 32.

In an embodiment, the electronic component 21, the conductive element22, 32 and the encapsulant 23 are positioned on one side of the carrier20, and a plurality of conductive pads 202 are formed on the oppositeside of the carrier 20.

Therefore, since the conventional TSV is replaced with the conductiveelement, the present disclosure fabricates the package structure throughcurrent packaging processes, dispensing with the conventionalTSV-related processes. As such, the present disclosure reduces thefabrication cost, shortens the fabrication time and improves the productyield.

The above-described descriptions of the detailed embodiments are only toillustrate the implementation according to the present disclosure, andit is not to limit the scope of the present disclosure. Accordingly, allmodifications and variations completed by those with ordinary skill inthe art should fall within the scope of present disclosure defined bythe appended claims.

1-8. (canceled)
 9. A method for fabricating a package structure,comprising: disposing at least one conductive element and an electroniccomponent having a sensing surface on a carrier; forming on the carrieran encapsulant encapsulating the electronic component and the conductiveelement, with the sensing surface of the electronic component and aportion of a surface of the conductive element exposed from theencapsulant; and forming on the encapsulant a conductive layerelectrically connecting the conductive element and the electroniccomponent.
 10. The method of claim 9, wherein the carrier is a circuitboard or a lead frame.
 11. The method of claim 9, wherein the electroniccomponent is a fingerprint identification chip.
 12. The method of claim9, wherein the conductive element is a loop-type bonding wire or a wiresegment.
 13. The method of claim 9, wherein the conductive element iselectrically connected to the carrier.
 14. The method of claim 9,further comprising forming an opening in the encapsulant to expose theportion of the surface of the conductive element.
 15. The method ofclaim 9, further comprising disposing a plurality of conductive pads onone side of the carrier.
 16. The method of claim 15, wherein theelectronic component, the conductive element and the encapsulant aredisposed on the other opposite side of the carrier.